Subscript indices must either be real positive integers or logicals

Greetings all,

Well, I've never seen this error before, and I did try making my imaginary parts real - still didn't help.

Here's my code if you will (the relevant parts, all things not shown are previously defined):

D = [5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25];

skin_depth_seawater = sqrt(2/sigma_helo_seawater*u*omega);

F_1 = 1;
r = sqrt(eta^2+i*omega*sigma_helo_seawater*u); 
V_1 = sqrt(r^2 + (2*i*sigma_helo_seawater/sigma_helo_seawater));

R(D,r) = real(V_1*F_1 - r)/(V_1*F_1 + r); %****

Now when I run the file, it gives me the "subscript indices must either be real positive integers or logicals" error at the line where I have **.

Can someone explain what I am doing wrong and where I need to correct it?

Thanks!

Answer 1

[Walter Roberson]

r = sqrt(eta^2+i*omega*sigma_helo_seawater*u);

will almost never be a positive integer, but you try to use r as a subscript in the output of the assignment.

[Jesse]

Walter, thanks for answering. So I guess it's a matter of changing the subscript to a different variable? Or am I completely off track here, since I do the same thing with D?

Thanks!

[Walter Roberson]

Your D contains only values that are purely integer-valued.

The "i*" in your expression suggests that r is likely the square root of an imaginary number, which will not be a real positive integer when you try to store into R(D,r)

The problem isn't in storing imaginary numbers: the problem is trying to use an imaginary number as a subscript.

Try using

R(D,:) = (V_1*F_1 - r)/(V_1*F_1 + r);

[Jesse]

Awesome! Thanks Walter!